Current running thru your body will create an edy current and induce current into any Conductive ring worn on the body.
So when this happens you basically inducing a secondary voltage/current into the ring.
So you become a transformer.
This is why burn marks can happen on your body.
I've seen pics of fingers melted off due to this.
Its not just rings, I've even seen wrists burned from metal watch bands.
The worst I saw was caused from a car battery.
Most electricians even in the past will not ware a metal watch for this reason.